gms | German Medical Science

The innate immune system represents an ancient host defense mechanism. The most important effector mechanism of cell-mediated innate immunity is the production of antimicrobial peptides (AP) in response to pathogens. The purpose of the study was to determine whether human bone express antimicrobial peptides under regular conditions and to investigate potential differences in case of inflammatory bone disease. Moreover we examined the AP-expression on cultivated osteoblast cells (HOB) in stimulation experiments.

Healthy and inflamed bone were prepared for immunohistochemistry and RT-PCR. Quantification of the AP-mRNA was done with Real-Time RT-PCR. The cultivated human osteoblast cells (HOB) were used for stimulation experiments. The alteration of the AP-expression in presence of proinflammatory cytokines or bacteria was assessed by RT-PCR, Real-Time RT-PCR, immunohostochemistry and ELISA.

Immunohistochemistry and RT-PCR revealed different antimicrobial peptides in healthy bone and the osteoblast culture. The expression pattern of the AP changed in case of inflammatory bone disease. The stimulation experiments revealed the increase of the inducible beta defensins-3 on transcript and on protein-level in presence of proinflammatory cytokines and bacteria.

The human bone produces a variety of antimicrobial peptides. Under inflammatory conditions the expression pattern of the antimicrobial peptides changes. Natural HBD-3 protein shows antimicrobial effects even to multiresistant Staph. aureus in-vitro, so it may be useful in the treatment of inflammatory bone disease in future. The role of the antimicrobial peptides in inflammatory bone disease awaits further elucidation.